This question was asked during QA interview. What is SQL data conditioning?
Is it creating test data using SQL scripts to test different scenarios?
When someone asks me a question and I don't know the answer, I tell them I don't know the answer, and then I ask them to tell me what they think the answer is. Maybe you should do that next time. If you're an interview, I don't think you'll be judged worse for asking, since either way the interviewer already knows that you don't have the answer. And it's entirely possible that while you're not familiar with the term they're using, you actually know something about the subject -- which is all the interviewer really cares about anyway.
Here is what a few Google searches turned up. For seismic data, that seems to mean applying a noise filter so that the signal is stronger. A Teradata documentation page describes data conditioning in terms of renaming database columns, or creating new fields by concatenating other fields, or assigning NULL values to a column based on certain criteria. This web page for a marketing company refers to data conditioning in terms of reconciling a part number database against the part numbers of the company's supplies.
Based on those results, "data conditioning" seems to refer to cleaning up a data set before making it available for processing.